Complex formulas were historically expensive, and use in engineering and science therefore limited. Invention of symbols involving the no-cost super and subscript was much more frequent.

In practive, MathML etc. is not currently supported, and does not correspond with the frequency of use of super- and subscript in engineering and science. LaTeX is, on the other hand, more common and known to many publishing in physics, engineering, or math (but few inther sciences).

LaTeX is rendered very poorly in browsers which do not have built-in support for MathML, typically with coarse raster images, and font, size and aliasing mismatch.